On 23/08/2019 12:11, Robin Murphy wrote:
On 23/08/2019 03:12, Rob Herring wrote:
There is no point in resuming the h/w just to do flush operations and
doing so takes several locks which cause lockdep issues with the
shrinker.
Rework the flush operations to only happen when the h/w is already awake.
This avoids taking any locks associated with resuming.
Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
Cc: Steven Price <steven.price@xxxxxxx>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@xxxxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
---
v2: new patch
drivers/gpu/drm/panfrost/panfrost_mmu.c | 41 ++++++++++++-------------
1 file changed, 20 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c
b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index 842bdd7cf6be..ccf671a9c3fb 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -220,6 +220,23 @@ static size_t get_pgsize(u64 addr, size_t size)
return SZ_2M;
}
+void panfrost_mmu_flush_range(struct panfrost_device *pfdev,
+ struct panfrost_mmu *mmu,
+ u64 iova, size_t size)
+{
+ if (mmu->as < 0)
+ return;
+
+ /* Flush the PTs only if we're already awake */
+ if (!pm_runtime_get_if_in_use(pfdev->dev))
+ return;
Is the MMU guaranteed to be reset on resume such that the TLBs will
always come up clean? Otherwise there are potentially corners where
stale entries that we skip here might hang around if the hardware lies
about powering things down.
Assuming runtime PM has actually committed to the power off, then on
power on panfrost_device_resume() will be called which performs a reset
of the GPU which will clear the L2/TLBs so there shouldn't be any
problem there.
As far as I can see from the code that is how pm_runtime_get_if_in_use()
works - it will return true unless the suspend() callback has been called.
Steve
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